Incorrect billing nightmare

Vodacom is really unfair and treats its customers like they mean nothing to their business. How can their own mistake affect us this much?. All I am waiting for now is to get this mattervsorted, get the settlement letter and move to another service provider. They have been billing us incorrectly for way too long, they add advance on the invoices although we settlebthem and to make it worse our statements is forever going up and never down even though we pay. Our line has been cut for a month now, we paid over 500 out of desperation but now we told we owe over a thousand rands. Its really painful, we even had to get a new phone and number because they cannot help us. our contract was 110 and those year they changed it to 220 because they saw we load way too much airtime for business purposes. Now all of a sudden we owe so much money despite paying every month. If we owe over a thousand how did it come to that because they load airtime forbid? Shouldn't they have cut the line way back before we owed this much. We have called a million times and always get transfered from 1 department to the other. Our reference is ***.All we need is to get a correct statement and if they think we owe let them explain. We will pay and request a settlement so we move on. We tired of the treatment and its affecting us badly. All we need is to get the sim opened, get the letter and move on..